gallushi commented on a change in pull request #1871:
URL: https://github.com/apache/iceberg/pull/1871#discussion_r538459629
##########
File path:
core/src/main/java/org/apache/iceberg/hadoop/HadoopTableOperations.java
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@@ -161,8 +163,24 @@ public void commit(TableMetadata base, TableMetadata
metadata) {
"Failed to check if next version exists: %s", finalMetadataFile);
}
- // this rename operation is the atomic commit operation
- renameToFinal(fs, tempMetadataFile, finalMetadataFile);
+ if (useAtomicWrite) {
+ // using atomic write
+ try {
+ TableMetadataParser.write(metadata,
io().newOutputFile(finalMetadataFile.toString()));
+ } catch (RuntimeIOException e) {
+ CommitFailedException cfe = new CommitFailedException(
+ "Failed to commit changes using atomic write: %s",
finalMetadataFile.toString());
Review comment:
> How do you know that the `RuntimeIOException` indicates a write
conflict?
we can't really know that.
if the write fails due to a conflict, an `IOException` will be thrown in
`FSDataOutputStream.close(...)`, it will be caught in
`TableMetadataParser.internalWrite(...)` and a `RuntimeIOException` will be
thrown.
it will be tricky to identify that this is due to a conflict, since:
1) other problems might have caused the `IOException` to be thrown.
2) the exception text will vary based on underlying FS implementation (for
example, for IBM COS if using Stocator as the connector, the exception message
will look something like
`Caused by: java.io.IOException: saving output gal/test/v1.metadata.json
com.amazonaws.services.s3.model.AmazonS3Exception: At least one of the
preconditions you specified did not hold. (Service: Amazon S3; Status Code:
412; Error Code: PreconditionFailed; Request ID.....`)
> Should we support a conflict exception in the `FileIO` that can be thrown
instead?
the exception might be thrown by the output stream (e.g., during
`close(...)`) - so IMHO changing the `FileIO` or even the `OutputFile` won't be
enough to allow identifying conflicts.
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